Final answer:
Histone H1 is involved in bringing two nucleosomes with modified histone H3K9me3 closer together through dimer formation, leading to further compaction of the chromatin fiber.
Step-by-step explanation:
Two nucleosomes with modified histone H3K9me3 can be brought closer together through the formation of a dimer involving histone H1. Histone H1 is a linker histone that binds to the nucleosomes and helps to compact the chromatin structure. It plays a role in stabilizing the higher order structure of chromatin by interacting with the linker DNA between nucleosomes. When histone H1 is involved in dimer formation, it brings the nucleosomes closer together, leading to further compaction of the chromatin fiber.
Non-histone proteins can bind to nucleosomes modified with H3K9me3, leading to the formation of a dimer that compacts chromatin structure and silences gene expression.
Two nucleosomes with modified histone H3K9me3 can be brought closer together through the formation of a dimer involving non-histone proteins that specifically recognize these modifications. These proteins can induce heterochromatin formation, leading to a more compact chromatin structure which makes the DNA less accessible for transcription. The chemical modifications, like methylation at histone H3 on lysine 9 (H3K9me3), play a crucial role in chromatin remodeling and gene regulation.
H3K9me3 is known to be associated with heterochromatin formation, which is a tightly packed form of DNA, indicating regions where gene expression is usually silenced. Histone methyltransferases add methyl groups to the histone tails, which can then serve as docking sites for the binding of proteins that promote condensation of the chromatin, such as heterochromatin protein 1 (HP1). The interaction between H3K9me3 and these proteins facilitates the close packing of nucleosomes, thereby inhibiting transcription.